In order to acquire a high-definition CT image, it is conceivable to reduce the bending of a table top of a bed. As one method for reducing the bending of the table top, there is known a method in which a frame that slidably supports the table top is moved as close as possible to a gantry. However, according to this method, since a clearance between the gantry and the frame decreases, the operable range of tilt angles is restricted. Although an interference can be avoided by restricting the tilt angle, the position of the frame, etc., it is not possible to exhibit to the maximum the capability of an X-ray computed tomography apparatus including this bed.